UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

MEMORANDUM 

DA TE: September 14, 20 15 

WASHINGTON, D.C. 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Rimsulfuron. Human Health Draft Risk Assessment for Registration Review. 

PC Code: 129009 

Decision No.: 500059 

Petition No.: NA 

DP Barcode: D425703 

Registration No.: NA 

Regulatory Action: Registration Review 

Risk Assessment Type: Single Chemical Aggregate Case No.: 72 I 8 

TXR No.: NA CAS No.: 12293 1-48-0 

MRID No.: NA 40 CFR: § 180.478 

FROM: 

THROUGH: 

TO: 

Minerva rcado-Felician~1 / oxic I t ~ 

Kristin Rury, Biologist (!f,1/ '-t;:.~-.:::<t---

Meherct Negussie, Chemist /Ye.A erd ~(f ll.J'<f<_ t:. 

Risk Assessment Branch III 

Health Effects Division (7509P) 

C

Risk 

hris

Assessment 

tine Olinger, 

Bran

hi e~ch / ~ J /_ 

/--

~~ 

Health Effects Divisio 9P) 

Jose Gayoso, Chemical Review Manager 

Cathryn Britton, Risk Manager 

Risk Management and Implementation Branch II 

Pesti cide Re-Registration Division (7508P) 

This draft risk assessment (DRA) evaluates the existing uses of rimsulfuron as part of Registration 

Review. Rimsulfuron is a sulfonylurea (SU) herbicide. The Agency is reviewing all of the SU 

herbicides jointly under Registration Review. For rimsulfuron, significant changes relative to the 

last risk assessment (C. Walls, 0408722, 07/02/2014) include a new incidental oral point of 

departure (POD) selected to assess spray drift exposure/risk estimates, and re-evaluation of the 

dermal POD. All other PODs remain the same since the last risk assessment. Some studies used 

for endpoint selection have conservative No Observed Adverse Effect Level/Lowest Observed 

Adverse Effect Level (NOAEL/LOAEL) values that have not been updated to reflect current 

standards for evaluating toxicity studies. Updates would result in higher NOAEL/LOAEL values 

and, given the cutTent risk picture, would not impact the overall findings of the risk assessment. 
Rimsulfuron Human Health Risk Assessment DP No. D425703 

Table of Contents 

1.0 Executive Sun11nary ....................................................................... ........... ... ........... .......... ... 4 

2.0 I-IED Recommendations ............................................................................... ....................... 4 

2. 1 Tolerance Considerations ............. .... ................ ..... .... ... ........ ............................................ 4 

2.2 Data Deficiencies ............................. ................ ......................................... ....................... 5 

3.0 Introduction ... ........................................................ .... ............... .... ....... ..................... .... ........ 5 

3. 1 Use Profile & Anticipated Exposure Pathways ................................................................ 5 

3 .2 Consideration of Environmental Justice .............................. ............................................ 7 

4.0 1-iazard Characterization ..................................................... ................................................. 7 

4.1 Summary of Toxicological Effects ............................................ .......... .............. ........... ... 7 

4.2 Safety Factor for Infants and Children (FQPA Safety Factor) ...................................... ... 8 

4.3 Toxicity Endpoint and Point of Departure Selections ...................................................... 8 

4.4 Endocrine Disruption ............................ ..... .... ................................................................ 10 

5.0 Dietary Risk Assessment ................................................................................... .......... ...... 11 

5.1 Residue Chen1istry ..... .............................................................. .......................................... 11 

5 .2 Water Residue Profile .................................................................................................... 12 

5.3 Dietary (Food + Water) Exposure Assessment.. ............................................................ 13 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ......................... ........... 14 

6.1 Spray Drift .......................................................................................................................... 14 

6. 1. l Incidental Oral Risk Estimates From Lawn Deposition Adjacent to Applications 15 

6.2 Residential Bystander Post-Application In halation Exposure ........................................... 16 

7.0 Aggregate Exposure/Risk Characterization ......................... ............................... ............... 17 

8.0 Occupational Exposure/Risk Characterization .................................................................. 17 

8.1 Occupational Handler ................... .................... ................ .............................................. 17 

8.1. I Occupational Handler Exposure, Assumptions and Risk Estimate Equations ........... 17 

8. 1.2 Sununary of Occupational Handler Non-Cancer Exposure and Risk Estimate ......... 18 

8.2 Occupational Post-Application Exposure ...................................................................... 21 

8.2. l Occupational Inhalation Post-Application Exposure ................................................. 21 

8.2.2 Occupational Post-application Dermal Exposure Data and Assumptions .................. 21 

8.2.3 Restricted Entry Interval ................ ....................................... .... ... ........... .................... 22 

9.0 Cumulative Exposure/Risk Characterization ..................................................................... 23 

I 0.0 Public Health and Pesticide Epidemiology Data ............................................................... 23 

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11.0 References.......................................................................................................................... 24

Appendix A. Toxicology Profile ................................................................................................. 25

A.1 Toxicology Data Requirements...................................................................................... 25

A.2 Toxicity Profiles............................................................................................................. 26

Appendix B. Physical/Chemical Properties of Rimsulfuron and Metabolites.............................. 29

Appendix C. Review of Human Research ................................................................................... 31

Appendix D. International Harmonization .................................................................................. 32

Appendix E. DFR and TTR Data Waiver Rationale ................................................................... 33

Appendix F. Sulfonylurea Pesticide Class Dermal Toxicity Data............................................... 34
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1.0 Executive Summary

Rimsulfuron (1-[4,6-dimethoxypyrimidin-2-yl]-3-[3-ethylsulfonyl-2-pyridylsulfonyl]urea) is a 

systemic herbicide belonging to the sulfonylurea group of herbicides. It is currently registered to 

E. I. du Pont de Nemours and Co. (DuPont) for use on bushberries, caneberries, chicory, field 

corn, grapes, potatoes, soybeans, tomatoes, various tree fruits, and tree nuts for pre- and postemergence control of annual grasses, broadleaf weeds, and yellow nutsedge. Permanent 

rimsulfuron tolerances are currently established in 40 CFR §180.478. Since the last risk 

assessment (C. Walls, D408722, 07/02/2014) and the scoping document (C. Walls, D401381, 

05/21/2012), there have been no changes to the rimsulfuron use or residue profile. A new 

incidental oral point of departure (POD) was selected, and the dermal POD was re-evaluated. All 

other PODs remain the same since last risk assessment. It is important to note that if all 

NOAELs/LOAELs were re-evaluated according to current toxicological policies, they would be 

higher; therefore, this risk assessment is considered extremely conservative. Existing uses have 

been reevaluated here using updated occupational and dietary exposure assessment 

methodologies. A spray drift assessment was also conducted to evaluate exposure resulting from 

drift from agricultural applications to surrounding residential areas. There are no risk estimates 

of concern for the existing uses of rimsulfuron.

2.0 HED Recommendations

The existing US tolerances for pistachio (0.01 ppm) needs to be removed from 40 CFR 

§180.478(a), since this commodity is included in crop group Nut, tree, group 14-12 (0.01 ppm). 

The existing tolerances for citrus fruits, pome fruits, stone fruits, and tree nuts need to be revised 

to Fruit, citrus, group 10-10, Fruit, pome, group 11-10, Fruit, stone, group 12-12, and Nut, tree, 

group 14-12. The proposed tolerance changes are a result of revisions in the crop groups and are 

conversions from existing groups/subgroups. The revisions are presented in Table 2.1.

2.1 Tolerance Considerations

Tolerances for residues of rimsulfuron [N-((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)-3-

(ethylsulfonyl)-2-pyridinesulfonamide] are listed in 40 CFR §180.478 and are expressed in terms 

of rimsulfuron only. Permanent tolerances are established for residues of rimsulfuron at levels 

ranging from 0.01 ppm in/on various tree fruits, tree nuts and grapes to 0.1 ppm in/on potatoes 

and field corn commodities [40 CFR §180.478(a)]. Tolerances are recommended for sorghum 

(grain, forage and stover) at 0.01 ppm each. The tolerance expression under 40 CFR 

§180.478(a) is correct and reflects measurement and compliance of rimsulfuron residues. 

Compliance with the tolerance levels is to be determined by measuring only rimsulfuron.

At this time, there are no Codex maximum residue limits (MRLs) established for residues of 

rimsulfuron. The US tolerances for bushberry subgroup 13-07B (0.01 ppm), field corn grain, 

potatoes, and tomatoes are harmonized with Canada. Canada has established an MRL at 0.05 

ppm on lowbush blueberries. There is a disharmony on livestock feedstuffs because Canada 

does not establish MRLs on feedstuffs. Refer to Appendix D. 
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Table 2.1. Tolerance Recommendations for Rimsulfuron

Commodity

Established 

Tolerance 

(ppm)

Recommended 

Tolerance (ppm) Comments

Fruit, citrus, group 10 0.01 0.01 Fruit, citrus, group 10-10

Fruit, pome, group 11 0.01 0.01 Fruit, pome, group 11-10

Fruit, stone, group 12 0.01 0.01 Fruit, stone, group 12-12

Nut, tree, group 14 0.01 0.01 Nut, tree, group 14-12

Pistachio 0.01 None Remove

Nut, tree, group 14-12 (0.01 ppm)

Bushberry, subgroup 13-07B 0.01 0.01 Bushberry subgroup 13-07B

Caneberry, subgroup 13-07A 0.01 0.01 Caneberry subgroup 13-07A

Grain, aspirated fractions 4.5 4.5 Grain, aspirated grain fractions

Corn, field, forage 0.4 0.40

Corn, field, grain 0.1 0.10

Potato 0.1 0.10

2.2 Data Deficiencies

There are no data deficiencies for rimsulfuron.

3.0 Introduction

3.1 Use Profile & Anticipated Exposure Pathways 

Rimsulfuron is formulated as dry flowable (DF) and liquid formulations. Currently registered 

labels include three technical/manufacturing use product labels, and 38 end use product labels. 

In general, rimsulfuron may be applied once or twice per year or growing season. Registered 

agricultural use sites include the following: acetolactate synthase (ALS) herbicide tolerant 

sorghum; blackberries; citrus fruit; field corn; field grown tomatoes and tomatoes for transplant; 

grapes; glyphosate resistant soybeans and corn; highbush and lowbush blueberries; pre-plant 

cotton, peanuts, and soybeans; pome fruit; potatoes and potatoes grown for seed; raspberries;

stone fruit; sulfonylurea herbicide tolerant chicory; and tree nuts. Registered non-agricultural 

use sites include sod farms, non-residential turf (including professional and college sports fields, 

commercial turf), golf courses, roadsides, industrial sites, utility substations, rangeland, and other 

non-crop sites. Rimsulfuron may be applied using groundboom, aerial, chemigation, and 

handheld application equipment. All the registered rimsulfuron labels require occupational 

handlers to wear long-sleeved shirts, long pants, shoes, and socks. All but two of the registered 

labels (EPA Reg. Nos. 67760-125 and 83100-42) require the addition of chemical resistant 

gloves. Some labels require the addition of a respirator, or protective eyewear. The restricted 

entry intervals (REIs) range from 4 hours to 24 hours on the registered rimsulfuron labels. Those 

products with additional PPE other than gloves, and REIs greater than 12 hours are all coformulated products with nicosulfuron, atrazine, dicamba, or isoxaflutole. 
Rimsulfuron Human Health Risk Assessment DP No. D425703

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Individuals may be exposed to rimsulfuron via their diet (food and drinking water). There are no 

registered uses for rimsulfuron that will result in direct non-dietary (i.e., residential) postapplication exposures. Additionally, there is the potential for indirect exposure (incidental oral 

and dermal) to rimsulfuron related to spray drift. Agricultural/occupational workers may be 

exposed (dermal and inhalation) to rimsulfuron during mixing, loading, and/or applying the 

herbicide as well as during post-application activities. Exposure to rimsulfuron is expected to be 

short- and intermediate-term for occupational handlers and post-application workers. However, 

since the toxicity POD is the same for both durations, the handler and post-application 

assessment is protective of both durations. Exposure to rimsulfuron via spray drift is expected to 

be short-term only. 

Table 3.1. Summary of Directions for Use of Rimsulfuron.

Applic. Timing, Type, and Equip. Formulation Max. Applic. Rate 

(lb ai/A)

Max. Seasonal Applic. Rate 

(lb ai/A)

Field Corn

Groundboom, Aerial, Chemigation

DF 0.031 0.062

Liquid 0.0079 0.063

Non Crop Sites1

Groundboom, Aerial, Handheld DF 0.063 0.063

Sod Farms, Seed Farms, Golf Courses, Professionally Managed Sports Fields, Industrial and Commercial 

Lawns, and Other Similar Non-Residential Areas

Groundboom, Handheld DF 0.016 0.063

Potatoes and Potatoes Grown for Seed

Ground, Aerial, Chemigation DF 0.023 0.039

Field Grown Tomatoes and Tomato Transplants

Ground and Handheld DF 0.063 0.063

Pome Fruit, Citrus Fruit, Tree Nuts, Stone Fruit, Grapes

Ground, Chemigation, Handheld DF 0.063 0.063

Pre-Plant Cotton and Soybeans

Ground, Aerial, Chemigation DF 0.021 0.31

Pre-Plant Peanuts

Ground, Aerial, Chemigation DF 0.016 0.31

Blueberry (Highbush and Lowbush) and Bushberry Subgroup 13-07B

Ground, Chemigation, Handheld DF 0.063 0.063

Caneberry (Raspberry and Blackberry) and Caneberry Subgroup 13-07A

Ground, Chemigation, Handheld DF 0.063 0.063

Chicory

Ground only DF 0.063 0.063

ALS Tolerant Sorghum

Ground, Aerial DF 0.016 0.50

Non-Residential Turfgrass

Ground, Aerial DF 0.031 0.031

1. Non-Crop use sites include: airports, highway, railroad, and utility rights of way; sewage disposal areas, uncultivated 

agricultural areas; non-crop producing areas. 
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3.2 Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in the 

preliminary human health risk assessment for rimsulfuron, in accordance with U.S. Executive 

Order 12898, "Federal Actions to Address Environmental Justice in Minority Populations and 

Low-Income Populations,"

http://www.epa.gov/compliance/resources/policies/ej/exec_order_12898.pdf. As a part of every 

pesticide risk assessment, OPP considers a large variety of consumer subgroups according to 

well-established procedures. In line with OPP policy, HED estimates risks to population 

subgroups from pesticide exposures that are based on patterns of that subgroup’s food and water 

consumption, and activities in and around the home that involve pesticide use in a residential 

setting. Extensive data on food consumption patterns are compiled by the USDA under the 

National Health and Nutrition Examination Surveys/What We Eat in America 

(NHANES/WWEIA) and are used in pesticide risk assessments for all registered food uses of a 

pesticide. These data are analyzed and categorized by subgroups based on age and ethnic group. 

Additionally, OPP is able to assess dietary exposure to smaller, specialized subgroups and 

exposure assessments are performed when conditions or circumstances warrant. Whenever 

appropriate, non-dietary exposures based on home use of pesticide products and associated risks 

for adult applicators and for toddlers, youths, and adults entering or playing on treated areas 

post-application are evaluated. Further considerations are currently in development as OPP has 

committed resources and expertise to the development of specialized software and models that 

consider exposure to bystanders and farm workers as well as lifestyle and traditional dietary 

patterns among specific subgroups. 

4.0 Hazard Characterization

The toxicology database for rimsulfuron is complete. The data requirements for a dermal 

toxicity study and a subchronic inhalation toxicity study are waived (J. Van Alstine, TXR 

0050008, 4/26/2012; K. Rury, TXR 0056438, 9/17/2012). The latest risk assessment was 

conducted in 2014 (C. Walls, D408722, 7/2/2014). No new toxicity and/or metabolism data 

have been received and the endpoints selected for the previous risk assessment remain the same

except for the dermal and incidental oral scenarios. A summary of the acute, subchronic, and 

chronic toxicity profile is presented in Appendix A.

4.1 Summary of Toxicological Effects

Rimsulfuron inhibits the plant enzyme acetolactate synthase (ALS)/acetohydroxy acid synthase 

(AHAS), leading to the disruption of cell division and elongation in the plant. ALS is not found 

in humans or other mammals. A gene coding for a similar protein has been found in humans; 

however, the protein or function associated with this gene is not known. Currently, the 

herbicidal mode of action of rimsulfuron is not relevant to mammals. 

After oral administration to rats, rimsulfuron is absorbed into the blood stream, mostly without 

metabolic changes before excretion. More than 90% of the dose was excreted within 72 hours, 

mostly as parent compound (47-71% of excreted compound). Urinary elimination accounted for 

about 64% of the dose and fecal elimination for about 30%. Low levels were found in the liver, 

heart, lung, kidney, and muscle 72 hours after a single dose. In addition to those organs, the 
Rimsulfuron Human Health Risk Assessment DP No. D425703

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spleen also had low levels of rimsulfuron after repeated doses. There were no major differences 

in absorption, distribution, metabolism or excretion between the sexes, except males showed 

more distribution to the liver than females. 

Dermal absorption studies are not available for rimsulfuron; however, an estimated maximum 

dermal absorption factor (DAF) of 20% is used in this risk assessment, based on the range of 

DAFs available from dermal penetration studies for other sulfonylureas (9.1-17.7%; see

Appendix F).

With repeated oral dosing, rimsulfuron produced very low toxicity in rats, mice, rabbits, and 

dogs. In most rat and mouse oral toxicity studies, the only effect seen at and above the limit dose 

(1000 mg/kg/day) was reduced body weight gain – which is not considered adverse in the 

absence of absolute body weight changes. In the dog, increased urinary volume and decreased 

osmolality occurred at 90 days, and kidney, liver and epididymis effects were observed at 52 

days. Male sex organ effects (microscopic changes in the testicular artery and tunica albuginea) 

were also observed in mice; but, only in a long-term study and only at doses above the limit 

dose. In a developmental toxicity study in rats, no maternal or fetal effects were found at doses 

above the limit dose. In a rabbit developmental study, no developmental effects were observed 

at doses that showed maternal death. A reproduction study in rats showed decreased body 

weight in adults and in female pups of the second generation on postnatal days (PND) 4 and 7 

(but not on PND 0 or 21), in animals dosed at or near the limit dose. Therefore, there is no 

evidence of increased qualitative or quantitative susceptibility in the young.

No increase in tumor incidence was seen in rats or mice, and rimsulfuron was not genotoxic, 

therefore it is not likely to be carcinogenic. There was no evidence of neurotoxicity or 

immunotoxicity in the database. The acute toxicity data indicate that rimsulfuron had low acute 

oral, dermal, and inhalation toxicity. Rimsulfuron was not found to be a skin irritant, but was a 

moderate eye irritant. Rimsulfuron was not a dermal sensitizer.

4.2 Safety Factor for Infants and Children (FQPA Safety Factor)

The toxicity database of rimsulfuron is complete and adequate to assess susceptibility in the 

young. There is no evidence of increased qualitative or quantitative susceptibility in the young, 

there is no evidence of neurotoxicity and exposure estimates are unlikely to underestimate risk; 

therefore, the FQPA Safety Factor (10X) is reduced to 1X.

4.3 Toxicity Endpoint and Point of Departure Selections

For rimsulfuron, a new incidental oral POD was selected, and the dermal POD was re-evaluated. 

All other PODs remain the same since last risk assessment (C. Walls, D408722, 07/02/2014). 

There has been no change to the prior cancer classification. Studies used for endpoint selection 

have conservative NOAEL/LOAEL values that have not been updated to reflect current 

standards for evaluating toxicity studies. Updates would result in higher NOAEL/LOAEL 

values and, given the current risk picture, would not impact the overall findings of the risk 

assessment.

Incidental Oral Endpoint (Short- and Intermediate-Term) for Spray Drift Exposure Scenarios: A 

90-day dog toxicity study was used to select the dose and endpoint for these scenarios. The 
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LOAEL of 125 mg/kg/day was based on increased urinary volume and kidney weights, and 

decreased osmolality. The NOAEL was 6.25 mg/kg/day. The 90-day dog study is appropriate 

for short- and intermediate-term exposure scenarios, and the endpoint is protective of decreased 

body weight observed in the reproductive study in F2 female pups on PND 7 and PND 14 at 

1316 mg/kg/day. The RAB3 risk assessment team recognizes that the incidental oral POD (6.25 

mg/kg/day) is similar to the chronic dietary POD (11.8 mg/kg/day). The incidental oral toxicity 

endpoint and NOAEL are considered conservative. If the study (90-day dog toxicity study) was

re-evaluated according to current toxicological practices, the study NOAEL/LOAEL would be 

higher. However such change in NOAEL (POD) would lead to larger MOEs than those 

currently calculated and therefore would not impact the findings of this risk assessment. 

Application of a 100-fold uncertainty factor (10X interspecies and 10X intraspecies) has been 

determined to be appropriate for the incidental oral exposure scenarios. The FQPA Safety Factor 

has been reduced to 1X as explained in section 4.3 above. 

Dermal Endpoints for Occupational and Non-Occupational Exposure Scenarios: A dermal 

endpoint was not selected for risk assessment. There is no 28-day dermal toxicity study 

available on rimsulfuron; however, the HED Hazard and Science Policy Council (HASPOC) 

recommended that the dermal toxicity study requirement be waived, based on a Weight of 

Evidence (WoE) approach (J. Van Alstine, TXR 0050008, 4/26/2012). A dermal risk assessment 

is not warranted because rimsulfuron is not expected to be toxic through the dermal route since:

(1) Rimsulfuron has low acute dermal toxicity (Category III), suggesting that the chemical 

either has low toxicity (in general) via the dermal route and/or is not absorbed via the 

dermal route in enough quantity to produce a systemic effect

(2) There is no quantitative offspring susceptibility in the toxicity database, therefore there is 

no concern for toxic effects on the young different from those on adults, via the dermal or 

any other routes of exposure, 

(3) Most sulfonylureas for which guideline dermal studies were submitted to the Agency 

showed no effects through the dermal route up to the limit dose (13 out of 15 studies; see 

Table F.2 in Appendix A); in fact the requirement for a guideline dermal toxicity study 

was waived for 7 sulfonylureas (including rimsulfuron) based on a weight of evidence 

that included consideration of the low dermal toxicity and low dermal penetration of the 

sulfonylurea class of pesticides (see Table F.3 in Appendix F) and 

(4) Dermal absorption is generally low (DAF < 20%) for sulfonylureas (see table F1 in 

appendix F). 
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Table 4.3.1. Summary of Toxicity Endpoints and Points of Departure for Rimsulfuron for Use in 

Human Risk Assessment.

Exposure

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

RfD, PAD, Level 

of Concern for 

Risk Assessment

Study and Toxicological 

Effects

Acute Dietary: All 

populations An endpoint attributable to a single dose was not identified in the database.

Chronic Dietary: All 

populations

NOAEL= 11.8

mg/kg/day

UFA = 10

UFH = 10

FQPA SF = 

1X

Chronic RfD =

0.118 mg/kg/day

cPAD = 0.118

mg/kg/day

Combined Chronic/ 

Carcinogenicity – Rat

LOAEL = 121 mg/kg/day 

based on decreased body 

weight gains and liver effects.

Incidental Oral: 

Short- and 

Intermediate-Term

NOAEL= 6.25

mg/kg /day 

UFA = 10

UFH = 10

FQPA SF = 

1X

Residential LOC 

for MOE = 100

90-day toxicity study – Dog

LOAEL = 125 mg/kg/day 

based on increased urinary 

volume, kidney weights, and 

decreased osmolality.

Inhalation Exposure: 

Short- and 

Intermediate-Term

NOAEL= 6.25

mg/kg /day

Inhalation 

toxicity assumed 

to be equivalent 

to oral.

UFA = 10

UFH = 10

Occupational 

LOC for MOE = 

100

90-day toxicity study – Dog

LOAEL = 125 mg/kg/day 

based on increased urinary 

volume, kidney weights, and 

decreased osmolality.

Dermal Exposure: 

Short- and 

Intermediate-Term

A dermal endpoint was not selected because rimsulfuron is not expected to be toxic 

through the dermal route.

Cancer (oral, dermal, 

inhalation) Not a carcinogen based on the lack of evidence of carcinogenicity in the rats and mice.

UF = uncertainty factor, FQPA SF = FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest observed 

adverse effect level, PAD = population adjusted dose (a = acute, c = chronic) RfD = reference dose, MOE = margin of exposure, 

LOC = level of concern, FQPA = Food Quality Protection Act. 

4.4 Endocrine Disruption

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its most recent registration decision for rimsulfuron , EPA 

reviewed these data and selected the most sensitive endpoints for relevant risk assessment 

scenarios from the existing hazard database. However, as required by FFDCA section 408(p), 

rimsulfuron is subject to the endocrine screening part of the Endocrine Disruptor Screening 
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Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of 

chemicals identified for EDSP screening was published on June 14, 20131and includes some 

pesticides scheduled for Registration Review and chemicals found in water. Neither of these 

lists should be construed as a list of known or likely endocrine disruptors. 

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our website.2

5.0 Dietary Risk Assessment

The residue chemistry data and environmental fate data are adequate to assess human exposure. 

The dietary exposure assessments are considered conservative and based on reliable data and 

will not underestimate exposure/risk. An unrefined chronic dietary assessment was conducted 

using tolerance level residues, default processing factors, and assuming 100% of the crops were 

treated for the registered crop uses. 

5.1 Residue Chemistry

The nature of the residue of rimsulfuron in plants and livestock has been adequately delineated 

based on metabolism studies conducted with rimsulfuron in field corn, potatoes, tomatoes, 

lactating goats, and laying hens. The metabolic pathways were found to be similar in plants and 

livestock. The major route of rimsulfuron metabolism/degradation involves sulfonylurea bridge 

contraction, with sulfonylurea bridge cleavage as a minor metabolic route. HED has determined 

that the residue of concern (ROC) for tolerance enforcement and risk assessment is the parent 

 

1 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals.

2 http://www.epa.gov/endo/
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compound (rimsulfuron) for plants and livestock commodities. 

Table 5.1. Compounds to be Included in the Rimsulfuron Risk Assessment and Tolerance 

Expression.

Matrix Residues included in Risk 

Assessment

Residues included in Tolerance 

Expression

Plants Primary Crop Rimsulfuron Rimsulfuron

Rotational Crop Rimsulfuron Rimsulfuron

Livestock Ruminant Rimsulfuron Rimsulfuron

Poultry Rimsulfuron Rimsulfuron

Drinking Water Rimsulfuron, IN-70941 and IN-70942 Not Applicable

The residue chemistry database is adequate to support current Registration Review data 

requirements. Adequate metabolism, field trial and processing studies are available to support 

the registered uses. The magnitude of the residue and processing studies are supported by 

adequate storage stability data for rimsulfuron. Adequate methods are available for enforcement 

of the currently established tolerances. Based on the registered ruminant feed items, there is no 

reasonable expectation of finite residues of rimsulfuron in livestock commodities. Adequate 

confined rotational crop data are available to support minimum plant-back intervals up to 18 

months, depending on the end-use product.

Adequate high performance liquid chromatography methods with tandem mass spectroscopic 

detection (HPLC/MS/MS) are available for tolerance enforcement: Method DuPont-15033 for 

watery and dry crop matrices, Method DuPont-15027 for oily crop matrices; DuPont-17928 for 

grass, and DuPont-32277 for sorghum commodities. The validated limit of quantitation (LOQ) 

is 0.010 ppm in each matrix. An HPLC/UV (ultraviolet) method is available for tolerance 

enforcement for residues of rimsulfuron in/on corn, potato, and tomato commodities. The LOQ 

is 0.05 ppm. The methods have been adequately validated for the determination of residues of 

rimsulfuron in plants. 

Multi-residue methods testing data were previously submitted for rimsulfuron, which indicated 

that the methods are not applicable for rimsulfuron determination. 

An analytical reference standard for rimsulfuron with an expiration date of 03/10/2020 is 

available at EPA’s National Pesticide Standards Repository (e-mail dated 05/11/2015 from 

Theresa Cole, Analytical Chemistry Branch/Biological and Economic Analysis Division). 

The structure, physical/chemical properties, and structure of metabolites are summarized in 

Appendix B. 

5.2 Water Residue Profile 

Rimsulfuron foliar applications using ground and aerial sprays impact both surface water and 

groundwater drinking sources given that it possesses similar physical chemical properties and 

persistence to other chemicals which are known to translocate to these media. The drinking 

water residues used in the dietary assessment were provided by the Environmental Fate and 

Effects Division (EFED) in the following memorandum: “Tier I Drinking Water Assessment for 

the proposed Section 3 ALS inhibition tolerant sorghum crops new use for the chemical 
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Rimsulfuron”; (M. Barrett, D414506, 03/13/2014) and were incorporated directly into the dietary 

assessment. Water residues were incorporated in the DEEM Food Commodity Intake Database 

(FCID) into the food categories “water, direct, all sources” and “water, indirect, all sources.” 

Estimated drinking water concentrations (EDWCs) include total toxic residues of rimsulfuron 

and its degradates (IN-70941 and IN-70942) in accordance with the most recent memo of the 

Residues of Concern Knowledgebase Subcommittee (ROCKS; C. Walls, D416833, 12/18/2013). 

The estimates are based on the assessment of all registered uses using the Tier 1 model PRZMGW (Pesticide Root Zone Model-Ground Water). The maximum EDWCs are presented below 

in Table 5.2.

Table 5.2. Maximum Tier I Rimsulfuron EDWCs for drinking water based on application of 

rimsulfuron to crops with highest rates and exposure potential.1

Crops (scenario)

Highest Daily Value

(Acute)

Post-Breakthrough Average 

(Chronic and Cancer)

All 22.2 19.7

1 Based upon the highest values from six standard Tier 1 groundwater scenarios (i.e., a WI scenario based upon a 

predominantly corn production area). The EDWCs are representative for all registered crop use sites.

5.3 Dietary (Food + Water) Exposure Assessment

HED recently conducted an unrefined chronic dietary (food and drinking water) assessment for 

rimsulfuron (D418154, M. Negussie, 03/17/2014). The assessment was based on the assumption 

that rimsulfuron residues are present at tolerance levels in all commodities for which tolerances 

have been established and that 100% of those crops are treated. DEEM Version 7.81 default 

processing factors were applied to all processed commodities for which they were available. The 

groundwater EDWC of 19.7 μg/L from the Tier I PRZM-GW modeling was incorporated 

directly into the dietary assessment. 

Exposure and risk estimates were obtained from the Dietary Exposure Evaluation Model using 

the Food Commodity Intake Database (DEEM-FCID, version 3.16). The model uses food 

consumption data from the 2003-2008 NHANES/WWEIA (National Health and Nutrition 

Examination Survey, What We Eat in America) database, coupled with recipe files and residues 

in foods, to derive estimates of dietary exposure and risk. 

Generally, HED is concerned when the dietary exposure estimates exceed 100% of the acute or 

chronic population adjusted dose (aPAD or cPAD). The chronic dietary (food and drinking 

water) exposures to rimsulfuron are below HED’s level of concern (i.e., <100% of the aPAD or 

cPAD) for the general U.S. population and all population subgroups. The chronic dietary 

exposure estimates are <1% of the cPAD for the general U.S. population and 1.4% of the cPAD 

for infants (<1 year old), the most highly exposed population subgroup. Because of the 

conservative assumptions used in the analyses (tolerance level residues, 100% crop treated, 

default processing factors, and upper-bound modeled drinking water estimates), actual exposures 

and risks are expected to be lower than shown in Table 5.3. 

HED did not conduct an acute dietary exposure/risk assessment because an acute dietary POD 

was not selected for rimsulfuron. Rimsulfuron is considered “not likely to be carcinogenic to 
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humans”; therefore a cancer dietary risk assessment was also not conducted. 

Table 5.3. Chronic Aggregate Dietary (Food + Drinking Water) Exposure and Risk for 

Rimsulfuron.

Population Subgroup Exposure

(mg/kg/day) % cPAD

General U.S. Population 0.000807 <1

All Infants (< 1 year old) 0.001710 1.4

Children 1-2 years old 0.001658 1.4

Children 3-5 years old 0.001473 1.2

Children 6-12 years old 0.001002 <1

Youth 13-19 years old 0.000724 <1

Adults 20-49 years old 0.000743 <1

Adults 50-99 years old 0.000652 <1

Females 13-49 years old 0.000724 <1

6.0 Residential (Non-Occupational) Exposure/Risk Characterization

There are registered uses of rimsulfuron on sod farms, and golf courses; therefore, there is 

potential for post-application dermal exposure for adults and children. However, a quantitative 

residential post-application risk assessment was not conducted because there was no hazard 

identified for rimsulfuron via the dermal route of exposure. 

6.1 Spray Drift 

Off-target movement of pesticides can occur via many types of pathways and it is governed by a 

variety of factors. Sprays that are released and do not deposit in the application area end up offtarget and can lead to exposures to those it may directly contact. They can also deposit on 

surfaces where contact with residues can eventually lead to indirect exposures (e.g., children 

playing on lawns where residues have deposited next to treated fields). The potential risk 

estimates from these residues can be calculated using drift modeling onto 50 feet wide lawns 

coupled with methods employed for residential risk assessments for turf products.

The approach to be used for quantitatively incorporating spray drift into risk assessment is based 

on a premise of compliant applications which, by definition, should not result in direct exposures 

to individuals because of existing label language and other regulatory requirements intended to 

prevent them.1 Direct exposures would include inhalation of the spray plume or being sprayed 

directly. Rather, the exposures addressed here are thought to occur indirectly through contact 

with impacted areas, such as residential lawns, when compliant applications are conducted. 

Given this premise, exposures for children (1 to 2 years old) and adults who have contact with 

turf where residues are assumed to have deposited via spray drift thus resulting in an indirect 

 

1 This approach is consistent with the requirements of the EPA’s Worker Protection Standard.
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exposure are the focus of this analysis analogous to how exposures to turf products are 

considered in risk assessment. 

In order to evaluate the drift potential and associated risks, an approach based on drift modeling 

coupled with techniques used to evaluate residential uses of pesticides was utilized. Essentially, a 

residential turf assessment based on exposure to deposited residues has been completed to 

address drift from the agricultural applications of rimsulfuron. In the spray drift scenario, the 

deposited residue value was determined based on the amount of spray drift that may occur at 

varying distances from the edge of the treated field using the AgDrift (v2.1.1) model and the 

Residential Exposure Assessment Standard Operating Procedures Addenda 1: Consideration of 

Spray Drift Policy. Once the deposited residue values were determined, the remainder of the 

spray drift assessment was based on the algorithms and input values specified in the recently 

revised (2012) Standard Operating Procedures For Residential Risk Assessment (SOPs). 

A screening approach was developed based on the use of the AgDrift model in situations where 

specific label guidance that defines application parameters is not available.1 AgDrift is 

appropriate for use only when applications are made by aircraft, airblast orchard sprayers, and 

groundboom sprayers. When AgDrift was developed, a series of screening values (i.e., the Tier 

1 option) were incorporated into the model and represent each equipment type and use under 

varied conditions. The screening options specifically recommended in this methodology were 

selected because they are plausible and represent a reasonable upper bound level of drift for 

common application methods in agriculture. These screening options are consistent with how 

spray drift is considered in a number of ecological risk assessments and in the process used to 

develop drinking water concentrations used for risk assessment. In all cases, each scenario is to 

be evaluated unless it is not plausible based on the anticipated use pattern (e.g., herbicides are 

not typically applied to tree canopies) or specific label prohibitions (e.g., aerial applications are 

not allowed). Section 6.1.1 provides the screening level drift related risk estimates. 

In many cases, risks are of concern when the screening level estimates for spray drift are used as 

the basis for the analysis. In order to account for this issue and to provide additional risk 

management options additional spray drift deposition fractions were also considered. These drift 

estimates represent plausible options for pesticide labels. 

6.1.1 Incidental Oral Risk Estimates From Lawn Deposition Adjacent to 

Applications

The spray drift risk estimates are based on an estimated deposited residue concentration as a 

result of the screening level agricultural application scenarios. Rimsulfuron is registered on 

multiple agricultural use sites, as well as on non-agricultural use sites, including sod farms, nonresidential turf (including professional and college sports fields, commercial turf), golf courses, 

roadsides, industrial sites, utility substations, rangeland, and other non-crop sites. Rimsulfuron

may be applied using groundboom, aerial, chemigation, and handheld application equipment. 

The recommended drift scenario screening level options are listed below: 

 

1 http://www.epa.gov/pesticides/science/models_pg.htm 
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 Groundboom applications are based on the AgDrift option for high boom height and 

using very fine to fine spray type using the 90th percentile results. 

 Aerial applications are based on the use of AgDrift Tier 1 aerial option for a fine to 

medium spray type and a series of other parameters which will be described in more 

detail below (e.g., wind vector assumed to be 10 mph in a downwind direction for entire 

application/drift event).1

Incidental oral risk estimates from drift onto residential areas were evaluated for rimsulfuron 

using the maximum registered application rate of 0.063 lb ai/A. This is protective of all the 

registered uses of rimsulfuron at lower application rates. The applicable LOC is 100; therefore 

MOEs < 100 are of concern. Adult and children 1 to <2 year old dermal risk estimates were not 

calculated because there was no dermal hazard identified in the rimsulfuron database. Children’s 

(1 to <2 year old) incidental oral risk estimates from indirect exposure to rimsulfuron-related to 

spray drift result in no risks of concern at field edge. 

Table 6.1. Children 1 to <2 Years Old Incidental Oral Risk Estimates (MOEs) Related to Spray 

Drift Exposure to Rimsulfuron from the Registered Agricultural Uses. 

Application 

Type

Spray Type/Nozzle 

Configuration

Appl. Rate 

(lb ai/A)

TTR 

(μg/cm2)

2 At Edge (LOC = 100)

Agricultural Applications1

Aerial Fine to Medium

0.063 0.0070

25,000

Groundboom High Boom Very fine

to Fine 35,000

1 Maximum registered application rate of rimsulfuron. This assessment is considered protective of all registered crops and use

sites with lower application rates. 

2 HED’s default assumption that 10% of the application is available for transfer on day 0 following the application and the 

residues dissipate at a rate of 10% each following day.

6.2 Residential Bystander Post-Application Inhalation Exposure

Volatilization of pesticides may be a source of post-application inhalation exposure to 

individuals nearby pesticide applications. The agency sought expert advice and input on issues 

related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act 

Scientific Advisory Panel (SAP) in December 2009, and received the SAP’s final report on 

March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The 

agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a 

subsequent Volatilization Screening Analysis.2 During Registration Review, the agency will 

 

1 AgDrift allows for consideration of even finer spray patterns characterized as very fine to fine. However, this 

spray pattern was not selected as the common screening basis since it is used less commonly for most agriculture. If 

assessors identify this use pattern it should be used as the screening criteria and deposition values associated with it 

are provided in Table 1 below. Justification for including this spray quality should be included in any assessment 

based on specific label directions for its use.

2 Available at: http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219.
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utilize this analysis to determine if data (i.e., flux studies, route-specific inhalation toxicological 

studies) or further analysis is required for rimsulfuron.

7.0 Aggregate Exposure/Risk Characterization

The Food Quality Protection Act of 1996 directs EPA to assess aggregate exposure to pesticide 

chemical residues, including all anticipated dietary exposures and all other exposures for which 

there is reliable information. In the case of rimsulfuron, aggregate exposure and risk estimates 

are equivalent to the dietary exposure and risk estimates in Section 6 and are not of concern. 

There are no registered uses for rimsulfuron that will result in direct non-dietary (i.e., residential) 

exposures. However, there is the potential for indirect non-dietary exposure (incidental oral and 

dermal) to rimsulfuron related to spray drift. Residential exposures resulting from spray drift are 

not included in the aggregate assessment because the likelihood of co-occurrence with dietary 

(food + drinking water) exposures is very low. 

8.0 Occupational Exposure/Risk Characterization

There is potential occupational dermal and inhalation exposure from the registered uses of 

rimsulfuron. However, there was no dermal hazard identified in the rimsulfuron toxicity 

database; therefore only inhalation risk estimates were calculated. 

8.1 Occupational Handler

8.1.1 Occupational Handler Exposure, Assumptions and Risk Estimate 

Equations

Application Rate: The maximum single application rates are listed in Table 8.1. Refer to 

Section 3.0 for a complete use pattern description.

Body Weight & Absorption Factor: The standard body weight (80 kg) was used in this risk 

assessment since the endpoint selected was not developmental and/or based on fetal effects. 

Since no inhalation absorption data are available, toxicity by the inhalation route is considered to 

be equivalent to the estimated toxicity by the oral route of exposure.

Unit Exposures: It is the policy of HED to use the best available data to assess handler exposure. 

Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, 

include PHED 1.1, and the AHETF database. Some of these data are proprietary (e.g., AHETF 

data), and subject to the data protection provisions of FIFRA. The standard values recommended 

for use in predicting handler exposure that are used in this assessment, known as “unit 

exposures”, are outlined in the “Occupational Pesticide Handler Unit Exposure Surrogate 
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Reference Table1.” HED policy on use of surrogate data, including descriptions of the various 

sources, can be found at the Agency website2. 

Area Treated: The area treated inputs were based on the Science Advisory Council for Exposure 

Policy 9.1: Standard Values for Daily Acres Treated in Agriculture (listed in Table 8.1).

Risk Estimate Equations: The algorithms used to estimate non-cancer exposure and dose for 

occupational handlers can be found in Table 8.1.

8.1.2 Summary of Occupational Handler Non-Cancer Exposure and Risk 

Estimate

All occupational handler scenarios for the registered uses resulted in MOEs greater than 100 at 

baseline level of risk mitigation (i.e., baseline attire with no gloves or respirator) or engineering 

control for aerial applications (i.e., enclosed cockpits); therefore, are not of concern. The lowest 

inhalation MOE of 790 is associated with mixing/loading a dry flowable formulation for aerial 

application to high acreage field crops; such as corn or soybeans. 

The Agency matches quantitative occupational exposure assessment with appropriate 

characterization of exposure potential. While HED presents quantitative risk estimates for human 

flaggers where appropriate, agricultural aviation has changed dramatically over the past two 

decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of 

their membership, the use of GPS for swath guidance in agricultural aviation has grown steadily 

from the mid 1990’s. Over the same time period, the use of human flaggers for aerial pesticide 

applications has decreased steadily from ~15% in the late 1990’s to only 1% in the most recent 

(2012) NAAA survey. The Agency will continue to monitor all available information sources to 

best assess and characterize the exposure potential for human flaggers in agricultural aerial 

applications.

HED has no data to assess exposures to pilots using open cockpits. The only data available is for

exposure to pilots in enclosed cockpits. Therefore, risks to pilots are assessed using the 

engineering control (enclosed cockpits) and baseline attire (long-sleeve shirt, long pants, shoes, 

and socks); per the Agency’s Worker Protection Standard stipulations for engineering controls, 

pilots are not required to wear protective gloves for the duration of the application. With this 

level of protection, there are no risk estimates of concern for applicators.

 

1 Available at: http://www.epa.gov/opp00001/science/handler-exposure-table.pdf

2 Available at: http://www.epa.gov/pesticides/science/handler-exposure-data.html
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Table 8.1. Occupational Handler Short- and Intermediate-Term Non-Cancer Exposure and Risk 

Estimates for Rimsulfuron. 

Exposure Scenario Crop or Target Level of 

Concern

Inhalation 

Unit 

Exposure 

(μg/lb ai)1

Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Inhalation

Baseline Dose 

(mg/kg/day)4 MOE5

Mixer/Loader

Mixing/Loading Dry 

Flowables for Aerial 

Application

Sod

100

8.96

0.031 lb ai/A 350 acres 0.00122 5,100

Field Crop, Typical6 0.063 lb ai/A 350 acres 0.00248 2,500

Field Crop, High 

Acreage7 0.063 lb ai/A 1200 acres 0.00846 740

Mixing/Loading Dry 

Flowables for Chemigation 

Application

Orchard/Vineyard8 0.063 lb ai/A 350 acres 0.00248 2,500

Field Crop, High 

Acreage7 0.063 lb ai/A 350 acres 0.00248 2,500

Mixing/Loading Dry 

Flowables for 

Groundboom Application

Golf Course 0.031 lb ai/A

40 acres

0.000139 45,000

Field-Grown 

Ornamental Crops10 0.063 lb ai/A 0.000283 22,000

Sod 0.031 lb ai/A 80 acres 0.000278 22,000

Orchard/Vineyard8

0.063 lb ai/A

40 acres 0.000283 22,000

Field Crop, Typical6 80 acres 0.000565 11,000

Field Crop, High 

Acreage7 200 acres 0.00141 4,400

Mixing/Loading Liquids 

for Aerial Application

Field Crop, High 

Acreage7

0.219

0.0079 lb 

ai/A

1200 acres 0.000026 240,000

Mixing/Loading Liquids 

for Groundboom 

Application

200 acres 0.00000433 1,400,000

Mixing/Loading Liquids 

for Backpack and 

Mechanically Pressurized 

Handgun Application

Rights of Way

0.0063 lb 

ai/gal 1000 gal

0.0000173 360,000

Mixing/Loading Dry 

Flowables for Backpack 

and Mechanically 

Pressurized Handgun 

Application

Rights of Way 8.96 0.000705 8,900

Applicator

Applying Sprays via Aerial 

Equipment

Sod

100

0.0049

0.031 lb ai/A

350 acres

0.00000067 9,400,000

Field Crop, Typical6

0.063 lb ai/A

0.00000135 4,600,000

Field Crop, High 

Acreage7 1200 acres 0.00000463 1,300,000

Applying Sprays via 

Groundboom Equipment

Golf Course

0.34

0.031 lb ai/A

40 acres

0.00000528 1,200,000

Field-Grown 

Ornamental Crops10 0.063 lb ai/A 0.0000107 580,000

Sod 0.031 lb ai/A 80 acres 0.0000105 600,000

Orchard/Vineyard8 0.063 lb ai/A 40 acres 0.0000107 580,000

Field Crop, Typical6 0.063 lb ai/A 80 acres 0.0000214 290,000
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Table 8.1. Occupational Handler Short- and Intermediate-Term Non-Cancer Exposure and Risk 

Estimates for Rimsulfuron. 

Exposure Scenario Crop or Target Level of 

Concern

Inhalation 

Unit 

Exposure 

(μg/lb ai)1

Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Inhalation

Baseline Dose 

(mg/kg/day)4 MOE5

Field Crop, High 

Acreage7 0.063 lb ai/A 200 acres 0.0000535 120,000

Applying Sprays via 

Mechanically Pressurized 

Handgun

Rights-of-Way 8.68 0.0063 lb 

ai/gal 1000 gal 0.000684 9,100

Flagger

Flagging for Aerial 

Application

Sod

100 0.35

0.031 lb ai/A

350 acres

0.0000475 130,000

Field Crop, High 

Acreage7 0.063 lb ai/A 0.0000965 65,000

Mixer/Loader/Applicator

Mixing/Loading/Applying 

Sprays via Backpack 

Sprayers

Orchard/Vineyard8

100

2.58

0.0063 lb 

ai/A

40 gal

0.00000813 770,000

Landscaping, Turf 

(athletic fields, parks, 

etc)11 

0.0021 lb 

ai/gal 0.00000271 2,300,000

Industrial/Commercia

l Areas

30

0.0063 lb 

ai/gal 0.0000945 66,000

Mixing/Loading/Applying 

Sprays via Manually 

Pressurized Handwand

Landscaping, Turf 

(athletic fields, parks, 

etc)11 

0.0021 lb 

ai/gal

40 gal

0.0000315 200,000

Industrial/Commercia

l Areas

0.0063 lb 

ai/gal 0.0000945 66,000

Mixing/Loading/Applying 

Sprays via Mechanically 

Pressurized Handgun

Orchard/Vineyard8 3.9 0.0063 lb 

ai/gal 1000 gal 0.000308 20,000

Golf Course 42 0.021 lb ai/A 5 acres 0.0000551 110,000

Landscaping, Turf 

(athletic fields, parks, 

etc)11 

42 0.021 lb ai/A 5 acres 0.0000551 110,000

Industrial/Commercia

l Areas 3.9 0.0063 lb ai/gal 1000 gal 0.000308 20,000

Field Crop, Typical6 3.9 0.0063 lb 

ai/gal 1000 gal 0.000308 20,000

Loader/Applicator

Loading/Applying Dry 

Flowables and Liquids for 

Backpack Application

Rights of Way 100 69.1 0.0063 lb 

ai/gal 40 gal 0.000218 29,000

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (02/01/2015); Level of mitigation: Baseline. Note 

that aerial applicators are assessed as enclosed cockpit and baseline represents engineering controls. 

2 Based on registered rimsulfuron labels.

3 Exposure Science Advisory Council Policy #9.1.

4 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated 

or Amount Handled (A or gal/day) ÷ BW (80 kg).

5 Inhalation MOE = Inhalation NOAEL (6.25 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).
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6 “Field Crop, Typical” represents registered crops such as cranberries and tomatoes.

7 “Field Crop, High Acreage” represents registered crops such as corn, soybeans. Assessment is protective of other high acreage field crops with 

lower application rates, such as potatoes, peanuts, cotton, and chicory. 

8 “Orchard/Vineyard” represents registered crops such as citrus, stone fruit, tree nuts, pome fruit, grapes, blueberries and cranberries. 

9 “Field Crop, High Acreage” for liquids only registered for use on field corn. 

10 “Field Grown Ornamental Crops” to represent field grown tomatoes and tomatoes grown for transplanting.

11 Rimsulfuron is not registered for use on residential turf, but is registered for use on athletic fields and non-residential areas. 

8.2 Occupational Post-Application Exposure

8.2.1 Occupational Inhalation Post-Application Exposure

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical’s degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure.

There are multiple potential sources of post-application inhalation exposure to individuals 

performing post-application activities in previously treated fields. These potential sources 

include volatilization of pesticides and resuspension of dusts and/or particulates that contain 

pesticides. The agency sought expert advice and input on issues related to volatilization of 

pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel 

(SAP) in December 2009, and received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The agency has 

evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent 

Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQOPP-2014-0219). During Registration Review, the agency will utilize this analysis to determine 

if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is 

required for rimsulfuron.

In addition, the Agency is continuing to evaluate the available post-application inhalation 

exposure data generated by the Agricultural Reentry Task Force. Given these two efforts, the 

Agency will continue to identify the need for and, subsequently, the way to incorporate 

occupational post-application inhalation exposure into the agency's risk assessments.

Although a quantitative occupational post-application inhalation exposure assessment was not 

performed, an inhalation exposure assessment was performed for occupational/commercial 

handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in 

higher exposure than post-application exposure. Therefore, it is expected that these handler 

inhalation exposure estimates would be protective of most occupational post-application 

inhalation exposure scenarios.

8.2.2 Occupational Post-application Dermal Exposure Data and 

Assumptions

An occupational post-application dermal exposure assessment was not performed for rimsulfuron 
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because no dermal hazard was identified in the toxicity database. Therefore, an assessment of 

occupational dermal post-application exposure to rimsulfuron was not conducted. A chemicalspecific DFR study is not available for rimsulfuron and is not required at this time (Appendix E). 

8.2.3 Restricted Entry Interval

Based on the acute toxicity categories and post-application assessment for rimsulfuron, the 

Worker Protection Standard (WPS) Interim Restricted Entry Interval (REI) for rimsulfuron is 12-

hours. REIs may be further reduced if certain criteria are met in accordance with the Pesticide 

Registration (PR) Notice 95-3 [Reduction of WPS Interim REIs for Certain Low Risk 

Pesticides]1. In PR Notice 95-3, there are a set of criteria listed for the active ingredient that 

must be met for chemicals to be eligible for a reduced REI. These criteria include:

1. The active ingredient is in Toxicity category III or IV based upon data for acute dermal 

toxicity, acute inhalation toxicity, primary skin irritation, and primary eye irritation. 

Acute oral toxicity data were used if no acute dermal data were available. If EPA lacked 

data on primary skin irritation, acute inhalation, or primary eye irritation of the active 

ingredient, the Agency reviewed data on that end-point for similar active ingredients 

(analogs), and excluded such active ingredients from consideration for the reduced REI, 

if the analog is in Toxicity Category I or II for that endpoint.

2. The active ingredient is not a dermal sensitizer (or in the case of biochemical and 

microbial active ingredients, no known reports of hypersensitivity exist).

3. The active ingredient is not a cholinesterase inhibitor (NMethyl carbamate and 

Organophosphate) as these chemicals are known to cause large numbers of pesticide 

poisonings and have the potential for serious neurological effects.

4. No known reproductive, developmental, carcinogenic, or neurotoxic effects have been 

associated with the active ingredient. If active ingredients did not have data available for 

these chronic health effects, EPA considered data on appropriate chemical and biological 

analogs. Active ingredients that have been classified as carcinogenic in Category B 

(probable human carcinogen) or Category C with a potency factor, Q* (possible human 

carcinogen, for which quantification of potential risk is considered appropriate), or are 

scheduled for the Health Effects Division's Cancer Peer Review process, were omitted 

from consideration.

5. EPA does not possess incident information (illness or injury reports) that are ``definitely'' 

or ``probably'' related to post-application exposures to the active ingredient.

Upon review of the criteria for the active ingredient only, it appears that rimsulfuron is consistent 

with the criteria in PRN 95-3 that allow for a 4-hour REI. Note: The PR Notice also includes similar 

 

1 Available: http://www.epa.gov/PR_Notices/pr95-3.html
Rimsulfuron Human Health Risk Assessment DP No. D425703

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criteria for the end-use product. These criteria have not been evaluated by HED. Based solely on 

the active ingredient criteria, HED would recommend for reduction of the REI for rimsulfuron.

9.0 Cumulative Exposure/Risk Characterization

In 2015, EPA’s Office of Pesticide Programs released a guidance document entitled, Pesticide 

Cumulative Risk Assessment: Framework for Screening Analysis1. This document provides 

guidance on how to screen groups of pesticides for cumulative evaluation using a two-step 

approach beginning with the evaluation of available toxicological information and if necessary, 

followed by a risk-based screening approach. This framework supplements the existing 

guidance documents for establishing common mechanism groups (CMGs)2and conducting 

cumulative risk assessments (CRA)3. The Agency has utilized this framework to evaluate the 

SUs of which [chemical name] is a member (J. D’Agostino; D428798; 9/9/15). Although the 

SUs share some chemical and toxicological characteristics, the toxicological database does not 

support a testable hypothesis for a common mechanism of action. No further mechanistic data 

are required and no further cumulative evaluation is necessary.

10.0 Public Health and Pesticide Epidemiology Data

Evaluation of the OPP Incident Data System (IDS) (S. Recore, D402251, 5/8/12; includes 

incidents from January 1, 2007 through February 22, 2012) indicated that no single chemical 

rimsulfuron incidents were identified in the United States. In the aggregate IDS (which reports 

incidents of multiple chemical exposures at the same time) there were 9 incidents reported for 

rimsulfuron. Because they fall within the categories reported as counts (which includes minor, 

unknown or no effects), there is no unique report that provides details about the incident and 

single chemical incidents are not distinguished from multiple chemical incidents. A high 

frequency of incidents indicates there is a high potential for exposure and vice versa. However 

for rimsulfuron, there appears to be a low potential for exposure. Rimsulfuron is not included in 

the Agricultural Health Study (AHS), and therefore, the AHS does not provide information for 

this report. There does not appear to be a concern at this time that would warrant further 

investigation. The Agency will continue to monitor the incident information. If a concern is 

triggered, additional analysis will be included in the risk assessment.

 

1 http://www.epa.gov/oppfead1/cb/csb_page/updates/2015/framework-for-screening-analysis.html

2 Guidance For Identifying Pesticide Chemicals and Other Substances that have a Common Mechanism of Toxicity 

(USEPA, 1999)

3 Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common Mechanism of Toxicity 

(USEPA, 2002)
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11.0 References

Author Barcode Date Title

J. Van 

Alstine

TXR 

0050008

04/26/2012 Rimsulfuron: Summary of Hazard and Science Policy Council 

(HASPOC) Meeting of March 29, 2012: Recommendations on the 

need for a 28-day dermal toxicity study.

S. Recore D402251 05/08/2012 Rimsulfuron: Review of Human Incidents

K. Rury TXR 

0056438

09/17/2012 Rimsulfuron: Summary of Hazard and Science Policy Council 

(HASPOC) Meeting of August 9, 2012: Recommendations on the 

Requirement of Repeated Exposure Inhalation Study.

C. Walls D416833 12/18/2013 Rimsulfuron: Environmental Degradates Found in Drinking Water

M. Barrett D414506 03/13/2014 Tier I Drinking Water Assessment for the proposed Section 3 ALS 

inhibition tolerant sorghum crops new use for the chemical 

Rimsulfuron

M. 

Negussie

D418154 03/17/2014 Rimsulfuron Chronic Aggregate Dietary (Food and Drinking 

Water) Exposure and Risk Assessment for the Section 3 

Registration on Acetolactase Synthase (ALS) Tolerant Grain 

Sorghum.

C. Walls D408722 07/02/2014 Rimsulfuron. Human Health Risk Assessment for Proposed 

Section 3 Use on Acetolactase Synthase (ALS) Tolerant Grain 

Sorghum. 
Rimsulfuron Human Health Risk Assessment DP No. D425703

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Appendix A. Toxicology Profile 

A.1 Toxicology Data Requirements

Table A.1. Rimsulfuron Data Requirements

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity ......................................................

870.1200 Acute Dermal Toxicity .................................................

870.1300 Acute Inhalation Toxicity .............................................

870.2400 Primary Eye Irritation ...................................................

870.2500 Primary Dermal Irritation .............................................

870.2600 Dermal Sensitization.....................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent) ..............................................

870.3150 Oral Subchronic (nonrodent) ........................................

870.3200 21/28-Day Dermal ........................................................

870.3250 90-Day Dermal .............................................................

870.3465 90-Day Inhalation .........................................................

yes

yes

yes

no

yes

yes

yes

waived1

---

waived2

870.3700 Developmental Toxicity (rodent)..................................

870.3700 Developmental Toxicity (nonrodent)............................

870.3800 Reproduction.................................................................

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent) .............................................

870.4100b Chronic Toxicity (nonrodent) .......................................

870.4200a Carcinogenicity (rat).....................................................

870.4200b Carcinogenicity (mouse)...............................................

870.4300 Chronic Toxicity/Carcinogenicity (rodent)...................

yes

yes

yes

yes

no

yes3

yes

yes3

yes

yes3

870.5100 Mutagenicity—Gene Mutation - bacterial ....................

870.5300 Mutagenicity—Gene Mutation - mammalian ...............

870.5385 Mutagenicity—Structural Chromosomal Aberrations..

870.5550 Mutagenicity—Other Genotoxic Effects......................

yes

yes

yes

yes

yes

yes

yes

yes

870.6100 Acute Delayed Neurotox. (hen)....................................

870.6100 90-Day Neurotoxicity (hen)..........................................

870.6200a Acute Neurotox. Screening Battery (rat) ......................

870.6200b 90-Day Neurotoxicity Screening Battery (rat)..............

870.6300 Developmental Neurotoxicity.......................................

no

no

yes

yes

no

---

---

yes

yes

---

870.7485 General Metabolism......................................................

870.7600 Dermal Penetration .......................................................

870.7800 Immunotoxicity ............................................................

yes

no

yes

yes

---

yes

1 The requirement for this study has been waived (J. Van Alstine, TXR 0050008, 4/26/2012).

2 The requirement for this study has been waived (K. Rury, TXR 0056438, 9/17/2012).

2 A chronic/oncogenicity study is available for the rat, thus separate chronic and oncogenicity studies are not necessary.
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A.2 Toxicity Profiles

Table A.2.1. Acute Toxicity Profile – Rimsulfuron

Guideline No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral – rat 41356311, 41356310,

41931634

LD50 > 5000 mg/kg IV

870.1100 Acute oral – mouse 41931623 LD50 > 5000 mg/kg IV

870.1200 Acute dermal – rabbit 41356312, 41356313, 

41931624, 41931635

LD50 ≥ 2000 mg/kg III

870.1300 Acute inhalation – rat 41356314, 41931625, 

41931637, 41931636

LC50 ≥ 7.5 mg/L IV

870.2400 Acute eye irritation –

rabbit

41931626, 41356315, 

41356316, 41931638

Moderate eye 

irritant

III

870.2500 Acute dermal irritation –

rabbit 

41931627, 41356318

41931639, 41356317

Not an irritant IV

870.2600 Skin sensitization –

guinea pig 

41931628, 41356320, 

41931641, 41931640, 

41356319

Not a sensitizer NA

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Rimsulfuron

Guideline No./ Study 

Type

MRID No. (year)/ 

Classification /Doses

Results

870.3100

90-Day Oral Toxicity in 

Rodents (rat)

41356321 (1989)

Acceptable/guideline

0, 50, 1500, 7500, 2000 ppm

0, 2.5, 75, 375, 1000 mg/kg/day

NOAEL = 75 mg/kg/day

LOAEL = 375 mg/kg/day based on reduced body 

weight gains.

870.3100

90-Day Oral Toxicity in 

Rodents (mouse)

41356323 (1989)

Acceptable/non-guideline

0, 50, 375, 500, 7500 ppm

0, 7.5, 56, 225, 1125 mg/kg/day

NOAEL = 56 mg/kg/day males; >1125 females.

LOAEL = 225 mg/kg/day based on increased RBC 

and hemoglobin and decreased body weight gain and 

food efficiency in males (not established in females).

870.3150

90-Day Oral Toxicity in 

nonrodent (dog)

41356322 (1989)

Acceptable/guideline

0, 250, 5000, 20000 ppm

0, 6.25, 125, 500 mg/kg/day

NOAEL = 6.25 mg/kg/day

LOAEL = 125 mg/kg/day based on increased urinary 

volume and kidney weights and decreased 

osmolality.

870.3700a

Prenatal developmental in 

rodent (rat)

41356324 (1989)

Acceptable/guideline

0, 200, 700 , 2000 or 6000 

mg/kg/day

Maternal NOAEL = 6000 mg/kg/day

LOAEL could not be established.

Developmental NOAEL = 6000 mg/kg/day

LOAEL could not be established.

870.3700b

Prenatal developmental in 

nonrodent (rabbit)

41356325 (1989)

Acceptable/guideline

0, 25, 170 , 500 or 1500 

mg/kg/day

Maternal NOAEL = 170 mg/kg/day

LOAEL = 500 mg/kg/day based on death and 

reduced weight gain.

Developmental NOAEL = 500

LOAEL was not observed. Only two viable fetuses 

were available for evaluation at 1500 mg/kg bw/day.
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Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Rimsulfuron

Guideline No./ Study 

Type

MRID No. (year)/ 

Classification /Doses

Results

870.3800

Reproduction and Fertility 

Effects (rat)

41931644 (1990)

Acceptable/guideline

0, 50, 3000, 15000 ppm

M: 0, 2.8, 165, 830

F: 0, 3.4, 204, 1021 

mg/kg/day (F0)

M: 0, 3.7, 217, 1316 

F: 0, 4.3, 264, 1316 

mg/kg/day (F1)

Parental/Systemic NOAEL = 165 mg/kg/day 

LOAEL = 830 mg/kg/day based on decreased body 

weight and/or body weight gain in both sexes and 

generations.

Reproductive NOAEL = 1316 mg/kg/day

LOAEL could not be established.

Offspring NOAEL = 264 mg/kg/day

LOAEL = 1316 mg/kg/day based on decreased body 

weight in F2 female pups on PND 7 and PND 14.

870.4100

Chronic toxicity (dog)

41931643 (1991)

Acceptable/guideline

0, 50, 2500, 10000 ppm

M: 0, 1.6, 82, 342; F: 0, 1.6, 

87, 359 mg/kg/day

NOAEL = 82 mg/kg/day

LOAEL = 342 mg/kg/day based on decreased female

body weight; increased liver and kidney weights 

(both sexes); increased female serum cholesterol and 

ALP levels; increased incidence of seminiferous 

tubule degeneration and increased numbers of 

spermatid giant cells in epididymides in males. 

870.4200

Carcinogenicity (mouse)

4931642 (1991)

Acceptable/guideline

0, 25, 250, 2500, 7500 ppm

M: 0, 3.5, 36, 351, 1127; 

F: 0, 5.0, 51, 488, 1505 

mg/kg/day

NOAEL = 351 mg/kg/day

LOAEL = 1127 mg/kg/day based on decreased body 

weight (both sexes); increased incidence of glandular 

stomach dilation and cysts in males; testicular artery 

and tunica albuginea degeneration in males.

No evidence of carcinogenicity.

870.4300

Chronic 

Toxicity/Carcinogenicity 

(rat)

42047701 (1991)

Acceptable/guideline

0, 25, 300, 3000 or 10000 ppm 

M: 0, 1.0, 12, 121, 414; F: 0, 

1.4, 17, 163, 568 mg/kg/day

NOAEL = 12/163 mg/kg/day (male/female)

LOAEL = 121/568 based on decreased body weight 

gain and increased liver weight.

No evidence of carcinogenicity.

870.5100

Bacterial Reverse Mutation 

Test Salmonella 

typhimurium and/or E. coli)

42471310 (1992)

Acceptable/guideline

0, 10, 25, 50, 75, 100, 500, 

750, 1000 or 5000 μg/plate

DPX-E9636-22 was tested up to the limit 

concentration and was not mutagenic in the assay 

either with or without S-9 activation. The positive 

controls induced the appropriate responses in the 

corresponding strains. 

870.5300 

In vitro Mammalian Cell 

Gene Mutation Test

(Chinese hamster ovary cells)

41356328 (1989)

Acceptable/guideline

0, 10, 100, 250, 750 or 1300 

μg/mL

DPX-E9636-22 tested up to the limit of solubility. 

The positive controls induced the appropriate 

response. There was no evidence of induced mutant 

colonies over background.

870.5375 

In vitro Mammalian 

Chromosome Aberration 

Test (human lymphocytes)

41356329 (1989)

Acceptable/guideline

0, 100, 600, 1000 or 1300 μg/ml

DPX-E9636-22 tested up to the precipitating 

concentration. Positive controls induced the 

appropriate response. There was no evidence of 

Chromosome aberration induced over background.
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Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Rimsulfuron

Guideline No./ Study 

Type

MRID No. (year)/ 

Classification /Doses

Results

870.5385

Mammalian Bone Marrow 

Chromosome Aberration 

Assay (mouse)

41931622 (1989)

Acceptable/guideline

0, 500, 3000 or 5000 mg/kg

Compared to the vehicle control, no significant 

differences in the frequency of micronucleated cells 

were noted in the bone marrow cells from the 

animals treated with test compound.

870.5395

Mammalian Erythrocyte 

Micronucleus Test (mouse)

41356330 (1989)

Acceptable/guideline

0, 500, 3000 or 5000 mg/kg

DPX-E9636-22 tested up to the limit dose. Positive control 

induced appropriate response. No significant increase in 

the frequency of micronucleated polychromatic 

erythrocytes in bone marrow after any treatment time.

870.5550

Other Genotoxicity: 

Unscheduled D Synthesis 

(primary rat hepatocytes)

41356327 (1989)

Acceptable/guideline

0, 0.0008, 0.004, 0.008, 0.04, 

0.08, 0.4, 0.8, or 1.1 mg/mL

DPX-E9636-22 tested up to limit its concentration. 

The positive controls induced the appropriate 

response. There was no evidence that unscheduled D 

synthesis was induced.

870.6200a

Acute Neurotoxicity 

Screening Battery (rat)

48710302 (2011)

Acceptable/guideline 

0, 200, 1000, or 2000 mg/kg

NOAEL = 2000 mg/kg/day

LOAEL could not be established.

870.6200b

Subchronic Neurotoxicity 

Screening Battery (rat)

48710303 (2011)

Acceptable/guideline 

0, 1000, 3000, 75000 ppm

M: 0, 55, 170 or 438; F: 0, 

69, 193, 507 mg/kg/day

NOAEL = 438 mg/kg/day

LOAEL could not be established.

870.7485

Metabolism and 

Pharmacokinetics (rat)

42540701 (1989)

Acceptable/guideline

Single dose oral: 25 or 250 

mg/kg

Repeated dose oral: 25 

mg/kg/day for 15 days

No remarkable differences in excretion pattern between 

sexes. >90% dose excreted within 72 hours. 

Elimination: urine ~64% dose, feces ~30%, exhaled air 

<0.08%. Low but detectable amounts in heart, lung, 

liver, kidney, and muscle; repeat dose groups also 

showed accumulation in spleen. Hepatic accumulation, 

although low, slightly higher than other organs. Males 

showed more liver accumulation than females. Most 

urinary (42-55%) and fecal (5-16%) excretion was 

parent compound. Metabolism largely involved either 

contraction or cleavage of sulfonylurea bridge, followed 

by demethylation and subsequent hydroxylation. 

870.7800

Immunotoxicity (female 

mouse)

48710305 (2011)

Acceptable/guideline

0, 300, 600, 1800 or 6500 ppm

0, 45, 93, 288, 1006 mg/kg/day

NOAEL = 1006 mg/kg/day

LOAEL could not be established.
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Appendix B. Physical/Chemical Properties of Rimsulfuron and Metabolites

Table B.1. Rimsulfuron Nomenclature.

Compound

Common name Rimsulfuron

Company experimental name DPX-E9636

IUPAC name 1-(4,6-dimethoxypyrimidin-2-yl)-3-(3-ethylsulfonyl-2-pyridylsulfonyl)urea

CAS name N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-

pyridinesulfonamide

CAS registry number 122931-48-0

An analytical reference standard for rimsulfuron with an expiration date of 03/10/2020 is available at EPA’s 

National Pesticide Standards Repository (e-mail dated 05/11/2015 from Theresa Cole, Analytical Chemistry 

Branch/Biological and Economic Analysis Division). 

N S

O

N

O H

N

H

O N

N OCH3

OCH3

SO2C2H5

Table B.2. Physicochemical Properties of Technical Grade Rimsulfuron.

Parameter Value Reference

Melting point 172-173C Reviewed in DP# 

193018, M. Nelson, 

23/NOV/1993; 

Also, MRID No. 

47572805.

All product chemistry 

requirements reported to 

be fulfilled.

pH 4.32 to 5.89 (1% dilution in water)

Density 1.5032 ± 0.0016 g/cm3

Water solubility pH 5: 0.135 ± 0.005 g/L (25°C)

pH 7: 7.3 ± 0.03 g/L (25C)

pH 9: 5.56 ± 0.05 g/L (25C)

pH 4-4.5: 0.024 ± 0.001 g/L (20C)

Solvent solubility (25°C) N,N-dimethylformamide 241 ± 1 g/L

Dimethyl sulfoxide 113 ± 3 g/L

Methylene chloride 35.5 ± 0.4 g/L

Acetonitrile 17.2 ± 0.5 g/L

Acetone 14.8 ± 0.5 g/L

Ethyl acetate 2.85 ± 0.17 g/L

Methanol 1.55 ± 0.11 g/L

Toluene 0.363 ± 0.022 g/L

Xylene 0.093 ± 0.008 g/L

n-Hexane <0.01 g/L

Vapor pressure (25°C) <10-5 Pa

Dissociation constant, pKa 4

Octanol/water partition 

coefficient, Log(KOW)

pH 5: 1.94

pH 7: 0.0342

pH 9: not attempted

UV/visible absorption 

spectrum

pH 1.80 at 230 nm, ε = 1.78 x 104(log ε = 4.25) and at 290 mm, ε = 1.81x 102(log ε = 2.26)

pH 2.10 at 290 nm, ε = 2.03 x102(log ε = 2.31)

pH 5.03 at 240 nm, ε = 2.24 x 104(log ε = 4.35) and at 290 nm, ε = 4.81 x 102(log ε = 2.68)
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Table B.3. Chemical Names and Structures for Rimsulfuron Metabolites

Company code; Chemical name Chemical structure

IN—70941

N-(4 ,6-Dimethoxy-2-pyrimidinyl)-N-((3-ethylsulfonyl)-2-pyridinyl) 

urea

IN-70942

N-((3-ethylsulfonyl)-2-pyridinyl)-4,6-dimethoxy-2-pyrimidinamine

IN-E9260

3-(Ethylsulfonyl )-2-pyridinesulfonamide.

IN-T5831

N-(4,6-dimethoxy-2-pyrimidinyl)urea

IN-69190

2-amino-4,6-dimethoxy-5-pyrimidinol

IN-J290

2-Amino-4,6-dimethoxypyrimidine

IN-H1043

2-Amino-4,6-dihydroxypyrimidine

IN-JF999

N-[((3-Ethylsulfonyl)-2-pyridinyl)]-4-hydroxy-6-methoxy-2-

pyrimidineamine
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Appendix C. Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data are subject to ethics review 

pursuant to 40 CFR 26, have received that review, and are compliant with applicable ethics 

requirements. For certain studies that review may have included review by the Human Studies 

Review Board. Descriptions of data sources as well as guidance on their use can be found at: 

http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html.
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Appendix D. International Harmonization

TABLE D.1. Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex

40 CFR 180. 478 : (a) General:

rimsulfuron, N-((4,6-dimethoxypyrimidin2-yl)aminocarbonyl)-3-(ethylsulfonyl)-2-

pyridinesulfonamide)

N-[[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonyl]-3-

(ethylsulfonyl)-2-pyridinesulfonamide

None

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico1 Codex

Almond, hulls 0.09

Bushberry, subgroup 13-07B 0.01 0.01 aronia berries, buffalo currants, 

Chilean guavas, currants, elderberries, 

European barberries, gooseberries, 

highbush blueberries, highbush 

cranberries honeysuckle, huckleberries, 

jostaberries, lingonberries, native 

currants, salal berries, saskatoon berries 

(juneberries), sea buckthorn

0.05 lowbush blueberries

Caneberry, subgroup 13-07A 0.01

Chicory, roots 0.01

Chicory, tops 0.01

Corn, field, forage 0.4

Corn, field, grain 0.1 0.1 field corn

Corn, field, stover 2.5

Fruit, citrus, group 10 0.01

Fruit, pome, group 11 0.01

Fruit, stone, group 12 0.01

Grain, aspirated fractions 4.5

Grape 0.01

Nut, tree, group 14 0.01

Pistachio 0.01

Potato 0.1 0.1 potatoes

Soybean, forage 0.25

Soybean, hay 1.2

Soybean, hulls 0.04

Soybean, seed 0.01

Tomato 0.05 0.05 tomatoes

Recommended Tolerances (DP# D418153)

Sorghum, grain, grain 0.01

Sorghum, grain, forage 0.01

Sorghum, grain, stover 0.01

1 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.
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Appendix E. DFR and TTR Data Waiver Rationale

Dislodgeable Foliar Residue (DFR): In accordance with 40CFR158, DFR data are required for all 

occupational (e.g., crop, nursery, greenhouse use sites) or residential (e.g., ornamental and vegetable 

gardens, pick your own farms, retail tree farms) uses that could result in post-application exposure 

to foliage. In the absence of chemical-specific DFR data, EPA uses default values. The 2012 

Standard Operating Procedures for Residential Pesticide Exposure Assessment includes an analysis 

of a number of DFR studies, which resulted in the selection of a revised default values for the 

fraction of the application rate available for transfer after a foliar application (FAR). These values 

are based on an analysis of 19 DFR studies. Since that time, the Agricultural Re-entry Task Force

has submitted information (MRID 49299201) that corrects an application rate error made in the 

original submission of “ARF039 – Determination of Dermal and Inhalation Exposure to Reentry 

Workers During Chrysanthemum Pinching in a Greenhouse” (EPA MRID 45344501). As a result, 

the range of FAR values was revised from 2% - 89% to 2% - 47%. In the data, a large range of 

transferability is observed and this variability can potentially be attributable to many factors such as 

active ingredient; formulation; field conditions in the studies; weather conditions (e.g., humidity); or 

many other difficult to quantify factors. Although witnessed across multiple chemicals, this range 

in FAR values is not expected when considering DFR data for a single chemical. At this time, the 

ARTF submission did not alter the selection of 25% as the reasonable, high-end default value. 

Since there was no dermal POD selected for rimsulfuron, an occupational post-application 

assessment is not required at this time. Therefore, no additional DFR data are required and the 

40CFR DFR data requirement is waived. 

Turf Transferable Residue (TTR): In accordance with 40CFR158, TTR data are required for all 

occupational (e.g., sod farms, golf courses, parks, and recreational areas) or residential turf uses that 

could result in post-application exposure to turf. In the absence of chemical-specific TTR data, 

EPAuses default values. The 2012 Standard Operating Procedures for Residential Pesticide 

Exposure Assessment includes an analysis of all TTR data, available at the time, which resulted in 

the selection of revised liquid and granular default values for the fraction of the application rate 

available for transfer after a turf application (FAR). These values are based on an analysis of 59 TTR 

studies performed with the Modified California Roller Method (36 studies using liquids, 11 studies 

using wettable powders/water dispersible granules, and 12 studies using granules). The liquid 

results (N=131) indicate a range of FAR values from 0.0005% to 6.1% and the granular results 

(N=37) indicate a range of 0.00064% to 0.69%. In both the liquid and granular data, a large range 

of transferability is observed and this variability can potentially be attributable to many factors such 

as active ingredient; formulation; field conditions in the studies; weather conditions (e.g., humidity); 

or many other difficult to quantify factors. Although witnessed across multiple chemicals, this 

range in FAR values is not expected when considering TTR data for a single chemical. HED selected 

1% and 0.2% as high-end default values for liquid and granular products, respectively. Although TTR 

data are not available for rimsulfuron, post-application incidental oral exposure is not expected from 

the registered uses of rimsulfuron, and a quantitative dermal occupational or residential postapplication exposure assessment was not conducted due to the lack of toxicity via the dermal route 

of exposure to rimsulfuron. In this instance, it is unlikely that chemical-specific DFR data would be 

needed to further refine exposure assessments or would add appreciably to our overall 

understanding of the availability of turf transferrable residues for rimsulfuron. 
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Appendix F. Sulfonylurea Pesticide Class Dermal Toxicity Data

Table F.1. Structure-Activity Relationship (SAR) Data for Sulfonylureas Technical Formulations 

with Available Experimental or Estimated Dermal Absorption Factors (DAF)

Chemical MW Log Kow1 DAF DAF Basis/Dermal Penetration

Bensulfuron-methyl 410.4 0.79 4.7% Unpublished in vivo rat study not submitted to EPA 

(DuPont HLR 120-902). 

Chlorimuron-ethyl 414.8 2.50 4.8% Dermal NOAEL / oral LOAEL extrapolation.

3

Flazasulfuron 407.3 1.08 20%

Estimated maximum per SAR analysis (Log Kp = -

4.46). The closest SAR analog is tribenuron-methyl 

(Log Kp = -4.51, DAF = 17.7%).

Iododsulfuron-methylsodium 529.2 -0.70 11%

1-6% per in vivo rat study; however 11% used 

because data indicates absorption continues after 

exposure. 

Mesosulfuron-methyl 503.6 -0.48

An unacceptable/guideline rat in vivo study indicates 

11.9-26.3%. European document indicates 9% 

(SANCO/1 0298/2003-final2).

Nicosulfuron 410.4 -1.74 0.021-

0.23%

Unpublished in vitro human studies not submitted to 

EPA (DuPont 21540 and 255192).

Oxasulfuron 406.4 -0.81 1%

Unpublished in vitro rat and human, and in vivo rat 

studies not submitted to EPA (EC 

SANC0/4323/20022).

Primisulfuron 468.3 1.15 (pH 5.0) 30% Dermal NOAEL / oral LOAEL extrapolation.

3

Rimsulfuron 431.4 -1.46 20%

Estimated maximum per SAR analysis (Log Kp = -

6.41). The closest SAR analog is iodosulfuron (Kow 

= -6.24, DAF = 11%). 0.18-0.4% per unpublished in 

vitro human skin not submitted to EPA (DuPont 

24335, 25519 and 246002).

Tribenuron-methyl 395.4 0.78 17.7% Per in vivo rat study.

Trifloxysulfuronsodium 459.3 -0.42 30% Dermal NOAEL / oral LOAEL extrapolation3

Tritosulfuron 445.3 0.62 1%

Unpublished in vitro rat and human, and in vivo rat 

studies not submitted to EPA (EC SANC0/1256/08-

rev.12).

1 Log Kow measured at pH=7 unless otherwise indicated.

2 Concentrate chemical data excerpted in a DuPont submission, MRID 48904001. That document also has some dilute 

formulation DAFs, which were not considered here.

3 Calculated by dividing the dermal study NOAEL (when no LOAEL was observed) by a subchronic oral LOAEL. Because no 

dermal toxicity was observed, this will lead to an artificially high DAF.

Kp = skin permeation coefficient; calculated using the CDC/NIOSH Finite Dose Skin Permeation Calculator at 

http://www.cdc.gov/niosh/topics/skin/finiteskinpermcalc.html
Rimsulfuron Human Health Risk Assessment DP No. D425703

Page 35 of 36

Table F.2. Results of 21/28-Day Dermal Toxicity Studies (OCSPP 870.3200) for 

Sulfonylureas Technical Formulations.

Chemical Species LOAEL NOAEL Reference (MRID)

Chlorimuron-Ethyl Rabbit Not observed ≥ 1000 48646201

Foramsulfuron Rat Not observed ≥ 1000 45109608

Flazasulfuron Rabbit Not observed ≥ 1000 46220922

Halosulfuron-methyl Rat Not observed ≥ 1000 42661417

Imazosulfuron Rat Not observed ≥ 1000 47305236

Metsulfuron-methyl Rabbit 500

(dermatitis and diarrhea)

125 40357803, 41247801

Orthosulfamuron Rat Not observed ≥ 1000 46578911

Oxasulfuron Rat Not observed ≥ 1000 43414638

Primisulfuron Rabbit Not observed ≥ 1000 41337601, 41135302

Prosulfuron Rabbit Not observed ≥ 1000 42685235

Sulfometuron-methyl Rabbit Not observed ≥ 2000 00126714

Sulfosulfuron Rat Not observed ≥ 1000 44295752

Triasulfuron Rabbit 10

(dyspnea and ruffled fur)

Not observed 41585801

Trifloxysulfuron-sodium Rat Not observed ≥ 1000 45372004

Trisulfuron-methyl Rabbit Not observed ≥ 1000 42991409

Table F.3. Sulfonylureas with Waived 21/28-Day Dermal Toxicity Studies (OCSPP 

870.3200) Based on Weight of Evidence (WOE) Analysis.

Chemical Reference 

(TXR#, Date)

WOE Conclusion

Bensulfuronmethyl0056721, 

8/26/13

This approach considered all of the available hazard and exposure information, 

particularly that: (1) the low acute dermal toxicity (LD50 is > 2000mg/kg; 

Toxicity Category III) and 2) The use of an oral POD based on the most

sensitive endpoint (liver toxicity) observed in the most sensitive species (dog) 

after long-term exposure (1-year) with a high dermal absorption (75-100%) 

results in acceptable MOEs (>120) with 75% dermal absorption, or MOEs that 

are close to the level of concern (MOE = 93) with 100% dermal absorption. A 

longer term study is used to assess short and intermediate term exposure 

scenarios with high dermal absorption. Therefore, there is high confidence that 

the Agency is not underestimating risks in the absence of this study.

Chlorsulfuron 0056439, 

2/8/13

This approach considered all of the available hazard and exposure information 

for chlorsulfuron, including: (1) the low acute dermal toxicity (Toxicity 

Category III) of chlorsulfuron; (2) the use of an oral POD and assumption of 

100% dermal absorption for assessing dermal exposure that results in MOEs 

greater than 1,100 for risk via the dermal route from occupational exposure; 

and (3) results of dermal toxicity and dermal absorption studies from other 
Rimsulfuron Human Health Risk Assessment DP No. D425703

Page 36 of 36

Table F.3. Sulfonylureas with Waived 21/28-Day Dermal Toxicity Studies (OCSPP 

870.3200) Based on Weight of Evidence (WOE) Analysis.

Chemical Reference 

(TXR#, Date)

WOE Conclusion

members of this class that support low absorption and low dermal hazard.

Mesosulfuronmethyl0056562, 

2/21/13

This approach considered all of the available hazard and exposure information, 

particularly that: (1) the low acute toxicity of mesosulfuron-methyl (Toxicity 

Category IV); (2) relatively low dermal absorption (14%); and (3) the use of 

an oral POD assuming 100% dermal absorption factor resulted in MOEs 

(>7,300) that are greater than the Agency's LOC.

Nicosulfuron 0050011, 

8/2/12

This approach considered the following factors: 1) the relatively low dermal 

absorption rate (2-3%); 2) that there are no risk estimates of concern for any 

scenario from using the oral PODs (i.e., MOEs are greater than 1000); and 3) 

data from structurally related compounds that indicated that there is no 

evidence that dermal toxicity is a concern for nicosulfuron. When taken 

together, these lines of evidence (i.e., use pattern, labels require PPE, MOE 

risk estimates are not of concern without PPE, toxicity considerations) support 

the conclusion that a dermal toxicity study is not needed at this time.

Rimsulfuron 0050008, 

4/26/12

This approach considered all of the available hazard and exposure information, 

particularly that: 1) the available rimsulfuron structural analog data indicate 

that in the majority of cases, a 21- or 28-day dermal toxicity study will result 

in NOAELs ≥1000 mg/kg/day for sulfonylurea herbicides; and 2) the available 

rimsulfuron and sulfuron analog in vitro data indicate that dermal penetration 

of human skin is generally low.

Thifensulfuronmethyl0054114, 

3/7/12

The HASPOC considered the following factors: 1) discussed the potential for

differences in toxicity between the dermal and oral routes of exposure based 

on pharmacokinetic differences (i.e., dermal exposure by passes the liver); 2) 

the high dermal absorption (100%) rate assumed in the risk assessment; 3) the 

PODs used for dermal risk assessments could have been higher and resulted in 

higher MOEs due to more than 25-fold difference between the NOAEL and 

the LOAEL (i.e. because of the wide spacing between the doses, the true 

NOAEL is likely to higher); and 4) there are no risks of concern for any 

scenario from using the oral PODs (i.e., MO Es greater than 320). When taken 

together, these lines of evidence (i.e., use pattern, labels require PPE, MOE 

risk estimates are not of concern with PPE, toxicity considerations) support the 

conclusion that a dermal toxicity study is not needed at this time.

Tribenuronmethyl0056650, 

6/17/13

This approach considered all of the available hazard and exposure information, 

including: (1) the low acute toxicity of tribenuron methyl (Toxicity Category 

III); (2) that the use of an oral POD and the 18% dermal absorption factor 

resulted in MOEs ≥510; and (3) the POD use for assessing risk from 

intermediate term exposure could be higher due to dose spacing (i.e., there is a 

large gap between the NOAEL and the LOAEL), which would have resulted 

in higher MOEs.